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Study of food science involves the chemical and physical changes taking place when processed /cooked/ storage/preservation.
- Retention of nutritive value – primary consideration in the study of food science is the retention of nutrients during processing. Certain cooking methods and preparations at home may produce food loss of nutritive value to a considerable degree from reported value. It is important to cook/process the food with the maximum retention of nutrients.
- Palatability – Food is palatable, if taste is acceptable. Palatability involves various sensory impressions such as odor, taste, texture and other physical properties. Flavor is a complex quality, involving integration of sensations from the nasal cavity, the taste buds on the tongue and various movement sensors in the mouth. The primary taste sensations involving taste buds on the tongue are sweet, sour, bitter and salty. Taste is a combination of both odor and taste sensations. Certain individuals will have the sense of taste in defecting minute concentrations. The physical properties of foods such as texture, consistency and shape give a feeling or touch sensation. Texture is expressed as rough or smooth, coarse or fine, fluid or solid, moist or dry, compact or porous, tough or tender, hard or soft. Some amount of sugar may be sweeter at higher temperature than at lower temperature. Appearance also is extremely important. Without an attractive appearance, many foods are rejected without being tasted.
- Digestibility – factors affecting the rate at which food moves in GastroIntestinal Tract:
- Composition of the food
- Method of preparation
- Amount of food eaten
- Emotional state of the individual
- Physical activity during the digestive process
Foods high in fat usually stay in the stomach longer time, proteins next then carbohydrates least.
Methods of processing and preparation of food may influence
- rate
- ease or comfort
- completeness of digestion
Eg – hard cooked eggs are more completely digested than soft cooked eggs.
Exercise after meal lowers digestion rate
A mixed meal which contains required amounts of CHO, fat, protein, fiber is recommended as it is more digestible than any kind of meal containing deficient in one or two or some nutrients.
- Economy – at lower income levels, food costs represent a large proportion of the family budget. But there are some low cost foods which are nutritious too.
- To make food safe and wholesome - the following factors are to be considered.
- foods that naturally contain poisonous substances
- foods contaminated with pathogenic microbes
- foods contaminated with toxins produced by micro organisms
- foods contaminated with other substances during processing, before and after cooking
- Animal parasites : parasites such as tape worms, round worms contain species of protozoa may be common problems. Contaminated though foods or water carrying these infected agents.
- Pathogenic micro-organisms:
- Some pathogens are carried by food even though they are not grown in food.
- Others may grow in foods under certain conditions of temperature and other environmental factors destroying microbes.
- Cooking or pasteurization in some cases may avoid these conditions.
- Food toxins: Food poisoning may result from toxins produced by microbes. The microbes are destroyed by treating at temperature slightly below the boiling point.
Eg – Staphylococcus quarries – produces a potential toxin which is considered as a common cause of food poisoning.
It is important to prevent the formation of toxin by hygienic handling of foods and proper refrigeration. Certain animals may contain natural constituents that are toxic.
| Spinach & beet tops
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oxalic acid poisoning
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| Potato
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solanin (glycoallcaloid) (developed in sun exposed potatoes)
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| Ground nut
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aflotoxin ( aspergillus flavus) (Aflotoxin causes aflotoxicosis)
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| Cotton seed
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Gossypol
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| Soya bean
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Trypsin inhibitor
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Preventive measures –
- Proper washing (with germicidal H2O, salt H2O etc.)
- Proper cooking
- Proper storage
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Participants